KANT AND EVOLUTION 549 
formations which are the seeds of the future planets. For the particles, 
as they move round the sun in parallel circles and at not too great a 
difference of distance from the sun, are, by the equality of their parallel 
motion, almost at rest with respect to one another, and thus the attrac- 
tion of those particles which are of a higher specific attraction imme- 
diately produces an important effect, namely, the collection of those 
nearest one another so as to form a body which, in proportion to the 
growth of its mass, extends its attraction farther and draws elements 
from a wide region to unite with it in its further formation.” 
It must be left to mathematicians and astronomers to assess the 
precise merits of these speculations in comparison with those of Kant’s 
predecessors and successors in the same undertaking. But as to the 
historic affinities of Kant’s hypothesis the facts seem so clear that even 
a layman may pronounce upon them. The Kantian scheme is as dif- 
ferent from Laplace’s as any post-Newtonian cosmogony could well be. 
For it does not start with a gaseous, rotating, heated nebula; it does 
not explain the direction of revolution and rotation of the planets as 
derived from the rotation of a mass formerly cohering with that now 
constituting the sun; it does not regard the planets as having ever 
formed part of any such mass. It is well-known that the rings of 
Saturn suggested the most characteristic feature of Laplace’s theory. 
Kant has a chapter explaining these rings much as Laplace does; but 
he expressly insists that “the ring which surrounds Saturn was not 
acquired in the general way, nor has been produced by the universal 
laws of formation which have ruled the whole system of the planets.” 
On the other hand, it is not quite exact to identify (as does Hastie?®) 
Kant’s system of planetary evolution with the meteoritic hypothesis of 
Lockyer and G. H. Darwin. So far as I understand these matters, 
Kant’s cosmogony most nearly resembles an extremely recent doctrine 
upon the subject—the planetesimal hypothesis of Chamberlin and 
Salisbury. In the words of those authors: 
Under the typical form of that hypothesis it is assumed that the parent 
nebula of the solar system is formed of innumerable small bodies, planetesimals, 
revolving about a central gaseous mass much as the planets do to-day. The 
evolution of the system consisted in the aggregation of these innumerable small 
bodies into much fewer large ones. .. . The hypothesis, therefore, postulates no 
fundamental change in the system of dynamics after the nebula was once 
formed, but only an assemblage of the scattered material. The state of disper- 
sion of the material at the outset, as now, was maintained by orbital revolution, 
or, more closely speaking, by the centrifugal acceleration arising from revolu- 
tion.” 
*“ Kant’s Cosmogony,” 1900, p. Ixxxiv. At this date, of course, the 
planetesimal type of hypothesis had hardly been differentiated from the 
meteoritic. 
“Chamberlin and Salisbury, “ Geology,” 1906, IT., p. 38. The authors of 
this theory have failed to recognize in Kant an early prophet of their own doc- 
trine, and have referred to him, in the conventional manner, as h 
aving held a 
hypothesis “somewhat similar” to Laplace’s (Op. cit., p. 4) 
